Mediating effect analysis, as its name implies, is the middle process M to explore the influence of A on B, that is, to explore whether A affects B through the way of "A first affects M, and M then affects B".

M can be a variable or multiple variables, and it often appears as a continuous variable.

When A influences B through M 1, M2…Mn, M 1-Mn is a multiple intermediary; When A first affects M 1, M 1 then M2, and M2 then M3 ... Mn affects B, and M 1-Mn is a chain intermediary;